FKBP51 controls drug-induced NF-κB activaton in human leukemia. (A) Western blotting analysis of FKBP51 expression levels in cell lysates obtained from transfected or nontransfected Jurkat cells, with FKBP51 siRNA or the scrambled oligo as control. (B) Western blotting analysis of IκBα expression levels in cells transfected with FKBP51 siRNA and cultured with or without doxorubicin (5 μM) for 5 hours. (C) EMSA analysis of nuclear extracts from Jurkat cells transfected with FKBP51 siRNA and cultured with or without doxorubicin (5 μM) for 5 hours. A competition assay, with the same -κB cold oligo or an unrelated oligo (see “Materials and methods”), indicated the specificity of the NF-κB band.